The main scientific theme of this Center is to elucidate the role of mitochondrial Complex I dysfunction in the pathogenesis and pathophysiology of Parkinson's disease (PD). The presence of a mitochondrial Complex I defect in subjects with PD is now well established. This defect appears to arise as a consequence of abnormalities in mitochondrial DNA (mtDNA) and may be either inherited or acquired. The purpose of the Core is to support four projects aimed at: 1) sequencing mtDNA in PD subjects and controls; 2) characterizing mitochondrial structure and function in PD; 3) clarifying the genetic etiology of PD; and 4) elucidating the relationship between mitochondrial dysfunction and neuronal death. To that end, the Core is composed of four interactive and interdependent components: I) Administration; II) Subject Accrual and Ascertainment; III) Molecular genetics; and IV) Data Management and Biostatistics. The Administration Component (I) will oversee the entire operation of the Center and will serve all four projects as well as the balance of the Core. The Subject Accrual and Ascertainment Component (II) of the Core will accrue and fully characterize subjects with PD. THIS Core function is essential for all four projects. The ascertainment of multiplex families will serve Projects 1 and 3, while the Core function is ascertaining and validating the family history of subjects will serve Project 3 directly and the other Projects indirectly by further characterizing the subjects whose mtDNA may be incorporated into cybrids. The Molecular Genetic Component (III) will create cybrids to serve Projects 1, 2, and 4, screen subjects studied in Project 3 for previously described nuclear DNA mutations associated with PD, and bank nuclear and mitochondrial DNA on all subjects and controls. The Data Management and Biostatistics Component (IV) of the Core will serve all four projects; but particularly Project 3 which proposes complex segregation analysis and other statistical genetic analyses of gender effects on transmission of PD.